1. Field of the Invention
The present invention relates generally to the fields of polymers and high density compositions. More particularly, it concerns materials that may act as a replacement for lead in applications requiring lead's high density, but where the toxic effects of lead are undesirable. Further, the high density composites of the present invention may be employed in any application where a high density material is required.
2. Description of Related Art
Each year, approximately 689 million rounds of small arms ammunition (.22 caliber through .50 caliber) are fired during training by the Army, Navy, Air Force, Marine Corps, National Guard, and Reserves in the United States. An additional 10 million rounds are fired annually by the Department of Energy. The ammunition projectiles used for this training consist of lead antimony cores, or cores, encased in a copper alloy jacket. Use of these projectiles results in approximately 2,000 tons of lead per year being introduced into the environment. Lead contamination of soil, sediments, surface and groundwater have been confirmed through investigations conducted at Army, Navy, Air Force, Marine Corps, Coast Guard and private small arms ranges throughout the United States and Europe. Lead uptake in vegetation at a Marine Corps small arms range in Quantico, Virginia showed lead levels as high as 23,200 parts per million. Remediation of contaminated ranges has proven to be extremely expensive and provides only a temporary solution. The Navy reports hazardous waste removal from one small arms firing berm cost $2.5 million with an additional $100,000 per year required for lead contamination monitoring. Sixteen Navy small arms firing ranges are now required to improve hazardous waste maintenance at a predicted cost of $37.2 million. In addition, the September 1995 "Cost Analysis for Munitions Rule" prepared by the U.S. Army Concepts Analysis Agency indicate the cost to remediate an outdoor small arms range is approximately $150,000 per acre. Currently there are 120 ranges closing or scheduled to be closed as a result of Base Realignment and Closure recommendations which account for an estimated 4,185 acres or a total of $627 million.
In order for firing ranges to remain open, expensive cleanup procedures must be employed that provide only a temporary solution to the problem. A non-toxic, lead-free, environmentally safe, cost effective replacement projectile core material is required to enable firing ranges to remain open and to eliminate costly cleanup procedures. The density of the projectile should be close to that of a lead projectile for realistic performance simulation. Materials of a lower density decrease projectile range and penetration.
In addition, there is mounting concern over the use of lead shot for bird hunting, due to ingestion of the shot by birds and other animals as well as contamination of wetland areas. Indeed there has been legislation in the United States and other countries which bans the use of lead shots in waterfowl shots. Moreover, such a lead substitute or high density material will find many other applications, such as for weights, acoustic dampening or vibration dampening, and in radiation shielding applications, including protective clothing, medical clothing and clothing for use in nuclear reactors.